O
BJECTIVE:
How is the plankton
community at the West Antarctic Peninsula
structured and which
environmental parameters are driving respective
spatial differences?
The Western Antarctic Peninsula is climatically extremely variable and belongs to the fastest warming regions on earth.4
Introduction
Recent changes in the phytoplankton community composition from large diatoms to small
flagellated cryptophytes have been associated with regional climate change and are potentially
inducing further shifts in the dominance of major grazers in this region, i.e. Antarctic krill
(Euphausia superba) and salps (Salpa thompsoni).5, 6
This study is part of the project POpulation Shift and Ecosystem Response - Krill vs. Salps (POSER). The presented results will be complemented by further analyses, including microscopy, 16S sequencing, pigment analysis and flow cytometry. Furthermore, they will serve as basis for the analysis of experiments conducted on board that aimed at estimating the possible consequences
of a shift from the currently still predominant krill population to an increasing occurrence of salps.
We observed a highly diverse assemblage of protists at the
WAP. Community structure showed distinct differences among regions and depths, which were mainly determined by
temperature, depth, dissolved phosphate and latitude.
In order to enhance our understanding of these changes, compiling a comprehensive dataset characterizing the
regional plankton community structure and potential environmental drivers is crucial.
1 Institute for Chemistry and Biology of the Marine Environment, Carl von Ossietzky University of Ol- denburg
2 Alfred Wegener Institute, Helmholtz Centre for Marine and Polar Research
3 Helmholtz Institute for Functional Marine Biodiversity (HIFMB)
Samples were taken with a CTD at ten different stations and four different depths during the RV Polarstern cruise PS112 in late summer/autumn (March - May 2018) to the South Shetland Islands and the Antarctic Peninsula.
Methods
We used Illumina sequencing, targeting the 18S rDNA V4 region, to
investigate the protist community. The bioinformatic processing of the sequences was performed with a custom-made pipeline (Q-zip).7
Silva.v132 served as main reference for taxonomic annotations.
Most sequence reads belonged to dinoflagellates (42%), followed by the parasitic group of Syndiniales (12%) and diatoms (9%). Among
different stations and depths the relative abundances of taxonomic groups often varied considerably.
Temperature was the main factor contributing to the first axis (CAP1) and separated the Antarctic Sound (AS) samples from other regions.
Conclusions
Acknowledgements: We thank Stefan Neuhaus, Kerstin Oetjen, Swantje Rogge and Kai-Uwe Ludwichowski for their help and support. Special thanks go to captain and crew of the RV Polarstern.
This work was funded by the Ministry for Science and Culture of the State of Lower Saxony.
The large dissimilarities among SSI samples also coincided with a gradient in dissolved inorganic phosphate (PO4) concentrations.
28% of the dinoflagellate sequences were annotated as Gyrodinium, an often heterotrophic genus. More than half of the diatoms were identified as Thalassiosira (56%).
Quality control and filtering resulted in a diverse range of more than four million protist sequences and roughly
13 thousand operational taxonomic units (OTUs).
The dissimilarities along the second axis (CAP2) were mainly correlated to depth and led to a gradual clustering of South Shetland Island (SSI), Elephant Island (EI) and 200m samples.
Drake Passage samples displayed a clear separation of deep and shallow depths.
Dissolved silica (Si) and salinity also contributed significantly to the dissimilarity of samples but with lower correlation to the ordination axes.
Constrained Analysis of Principal
Coordinates (CAP) based on Bray-Curtis distances displaying the variation between protist assemblages, constrained by
relevant abiotic parameters and dissolved nutrient concentrations.
Outlook
Scan for further information:
Compositional Dissimilarity Community Composition
Marine protist diversity and
community structure at the West Antarctic Peninsula
Philipp Wenta
1, Christoph Plum
1, Dominik Bahlburg
1, Katja Metfies
2,3, Thomas Badewien
1, Stefanie Moorthi
14 Meredith et al. 2005, Geophys. Res. Lett., 32
5 Moline et al. 2004, Glob. Change Biol., 10: 1973-1980
6 Montes-Hugo et al. 2009, Science, 323: 1470-1473
7 Hardge et al. 2018, Mol Ecol Resour. , 18: 204–216
Metazoan OTUs were removed from the dataset and the number of reads were scaled to the smallest library size to account for
uneven sequencing depths.
Relative abundances of taxonomic groups at different stations and depths. Community composition varied significantly among different stations, depths and regions. DCM = Deep Chlorophyll Maximum
Drake Passage
Antarctic Sound Elephant Island
South Shetland Islands
